﻿<html>
<head>
<title>并集</title>
<style type="text/css">
  h1,h2,h3{
       color: purple;
   }
   h2.special,#one{
     text-decoration:underline;
}
</style>
</head>
<body>
   <h1>我是谁h1</h1>
   <h2 class="special">你是谁h2</h2>
   <h3>他是谁h3</h3>
   <h4 id="one">猜一猜h4</h4>
</body>
</html>
